This is an interesting topic. I’m in the middle of composing tunes for my game and a similar question hit me too: Will the effort be worthwhile?
I want to assume that all prize categories (except innovation) will make equal consideration about how well the sound/music works when it has a function. (la objectiveness)
On the other hand, the jury might as well weight graphics and sound (unequally) according to their contribution to atmosphere and overall impression. (la subjectiveness)